1. Field of the Invention
The present invention relates to a method of manufacturing an electrode for a secondary cell, and more particularly, it relates to a method of manufacturing an electrode for a secondary cell by forming an active material layer on a collector by a method supplying raw material from a gas phase.
2. Description of the Prior Art
A secondary cell is recently utilized in various fields related to electronic devices and the like. In particular, a lithium secondary cell is watched with interest as a new cell having a high output and high energy density. Various types of such lithium secondary cells are developed in general.
In relation to formation of an electrode active material in such a secondary cell, generally known is a technique of forming an active material layer on a collector by a method such as sputtering supplying raw material from a gas phase.
A conventional electrode for a secondary cell is inserted into a sheath while winding positive and negative electrodes thereby forming the cell. In this case, an active material layer does not contribute to charging/discharging if the same is present on the outermost or innermost periphery of the electrode. If the active material layer is present on the outermost or innermost periphery of the electrode, therefore, energy density is reduced. On the other hand, a tab (terminal part) for collection must be provided on the electrode. If the active material layer is present between the tab and a collector, therefore, a cell characteristic such as the cell voltage is disadvantageously reduced when the active material layer itself has low electric conductivity. Thus, the active material layer is preferably formed not on the overall surface but on a part of the collector.
In the aforementioned conventional method of forming an active material layer on a collector by a method such as sputtering supplying raw material from a gas phase, however, the active material layer is formed on the overall surface of the collector. In order to locate the active material layer on a part of the collector in this case, the active material layer formed on the overall surface of the collector must be partially mechanically separated from a portion of the collector requiring no active material layer.
However, the active material layer formed by sputtering or the like has large adhesion to the collector. Therefore, it is difficult to partially mechanically separate the active material layer formed on the overall surface of the collector from the portion of the collector requiring no active material layer.
Thus, in the conventional method of forming an active material layer on a collector by a method such as sputtering supplying raw material from a gas phase, it is disadvantageously difficult to partially remove the active material layer formed on the overall surface of the collector from the portion of the collector requiring no active material layer, and it is consequently difficult to locate the active material layer only on a necessary portion of the collector.